Telecoms operator Vodafone has been found to have breached consumer law, following a review by the Competition and Consumer Protection Commission.
The commission found the company was not providing adequate information to consumers on the various processes available to them for cancelling contracts and their legal rights.
As a result of the enforcement action, the company has been issued with a compliance notice directing it to amend and update the information on its website.
The action relates specifically to distance contracts, which are agreed remotely between Vodafone and customers over the phone or online.
Under the European Consumer Rights Directive, traders must give information to consumers about how they can cancel distance contracts within a set timeframe, prior to them making a purchase.
The review came on foot of complaints from consumers and follows similar compliance notices earlier this year issued to Eircom, eMobile, Meteor, Three and UPC.
In a statement, the commission's chairperson Isolde Goggin said that with more than half of adults in a recent survey saying they purchase goods or services online, consumers should be aware of the rights they have.
"Customers of Vodafone will in the future be given the correct information as required by law," Ms Goggin said.
"In addition, customers who bought goods or services online from Vodafone in the past twelve months and who now wish to cancel their contract can find details of how to do so in the customer notices section of the Vodafone website."
Vodafone said it "acknowledges the findings of the Competition and Consumer Protection Commission (CCPC) in relation to customers purchasing products and services through its online sales channel".
In a statement, it said: "Vodafone has now clarified this information on its website for customers who have purchased a product/service online through their e-shop, to ensure that the customer's cancellation rights are clearly outlined and easy to understand.
"Vodafone apologises to its online customers in relation to this matter.
"It has worked with the CCPC in relation to this issue and is confident that these matters have been fully dealt with and that the company's e-shop is now compliant with these requirements set out by the CCPC."